om tr14 054 0310 tr membrane
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EXPERIMENTAL MANUAL
MODEL: TR 14
SOLUTION ENGINEERING SDN. BHD.NO.3, JALAN TPK 2/4, TAMAN PERINDUSTRIAN KINRARA,47100 PUCHONG, SELANGOR DARUL EHSAN, MALAYSIA.
TEL: 603-80758000 FAX: 603-80755784
E-MAIL:[email protected]:www.solution.com.my
SOLTEQ EQUIPMENT FOR ENGINEERING EDUCATION
054-0310-TR
MEMBRANE TEST UNIT
MEMBRANE TEST
UNIT
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Table of Contents
List of Figures . i
1.0 INTRODUCTION 1
2.0 DESCRIPTION AND ASSEMBLY2.1 Membrane and membrane housing 52.2 Pumps . 52.3 Tanks and Cooling/Heating System 62.4 Water Flow Meter .. 6
3.0 SUMMARY OF THEORY 7
4.0 OPERATING PROCEDURES4.1 General Start-Up Procedures....114.2 General Shut-Down Procedures....11
5.0 EXPERIMENT PROCEDURES5.1 Membrane Characteristic Study ....12
6.0 SAFETY PRECAUTIONS AND MAINTENANCE ........13 6.1 Safety Precautions.13 6.2 Maintenance13
7.0 REFERENCES 14
APPENDICES
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List of Figures
Page
Figure 1 Process Schematic Diagram 2 Figure 2 A classification of major types of membrane processes 3
Figure 3 A typical crossflow operation includes recirculation loop 4
Figure 4 Tubular (multichannel) type of microfilter 7
Figure 5 Concentration polarization at a membrane surface. C w is the solute 9concentration at the membrane surface and C b is the bulk-soluteconcentration
Figure 6 Typical dependence of membrane flux. 9
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1.0 INTRODUCTION
New chemical separation techniques such as membrane separations are becomingincreasingly popular as it provides effective separation without the use of heating energy as indistillation processes. Heat sensitive materials can be separated or concentrated by virtue of
their molecular weights.
The Membrane Test Unit (Model: TR 14 ) is specially designed to allow students andresearchers to carry out the membrane processes that are widely used in biotechnology andprocess industries the Reverse Osmosis (RO), Nanofiltration (NF), and Ultrafiltration (UF).The process diagram is illustrated in Figure 1.
Ultrafiltration and microfiltration membranes are usually specified in terms of their "molecularweight cut-off" (MWCO), whereas the nanofiltration and reverse osmosis membranes arespecified in terms of their percentage rejection of salts. Polymeric membranes are widely
used and supplied in the form of modules that give membrane areas in the range of 1 - 20 m2
.The membranes that are supplied with the model TR 14 unit is classified as tubular type(Figure 2), which is widely used and have turbulent flow conditions. The system is in a crossflow configuration where the feed solution is pumped parallel to the membrane at a velocity inthe range of 1 - 8 ms -1
with a pressure difference of 0.1 - 0.5 MPa across the membrane. Liquidpermeates through the membrane and feed emerges in a more concentrated form on exit frommodule.
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Figure 1:Process Schematic Diagram
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Figure 2: A classification of major types of membrane processes
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The advantages of cross-flow membrane separations are
a) Higher overall liquid removal rate is achieved by preventing solid buildup on membrane surface. b) The concentrate (retentate) remains in a mobile form suitable for further processing.c) The solute content of the concentrate may be varied over a wide range.
d) It may be possible to fractionate solutes of different sizes.
CIRCULATION
SOLUTION TANK
CLEANING SOLUTION RETUM
FEED TANK
RECIRCULATION PUMP
SUSPENSION
RECIRCULATION
DRAIN/BLEEDCONCENTRATED
SUSPENSION
TI
PI
PI
FI
FI
PI
TI
FLOW INDICATOR
PRESSURE INDICATOR
TEMPERATURE INDICATOR
VALVE
FILTRATE
FEED
BANK OF CROSSFLOW FILTERS
Figure 3: A typical crossflow operation includes recirculation loop
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2.0 DESCRIPTION AND ASSEMBLY
2.1 Membrane and Membrane Housing
The P.C.I Single-tube Tester is designed for the economical, quick, initial evaluation ofmembrane types and processes for separation and concentration at laboratory scale priorto more detailed test work. It may be fitted with samples of any of PCIs wide range oftubular reverse osmosis, nanofiltration and ultrafiltration membranes. Simply constructed in316 stainless steel, the module has termination points allowing easy connection by flexibleor welded couplings to existing equipment.
The open channel, highly turbulent flow design allows a wide variety of process fluid to beconcentrated. It also allows simple clean-in-place techniques to be entirely effective.
The TR 14 unit is supplied with membrane:
i) Membrane 1: AFC 99 (Polyamide Film)
ii) Membrane 2: AFC40 (Polyamide Film)
iii) Membrane 3: CA 202 (Cellulose acetate)
iv) Membrane 4: FP 100 (PVDF)
The FP 100 PVDF membrane is rated with apparent retention character of 100000 MWCOand CA 202 is 2000 MWCO. In addition, the AFC40 has 60% CaCl 2 rejection and the
AFC99 is rated with 99% NaCl rejection.
2.2 Pump
2.2.1 CAT Triple Plunger Pump - Model 241
The CAT Triple Plunger pump is used to pump the liquid from the feed tank into themembrane module.
Specifications: Maximum flow rate : 13 liter/min.Working pressure range : 7-85 barMax. fluid temperature : 71 CMax. speed : 1725 RPMMax. horsepower : 3.0 HP
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A CPC 7002 Pressure regulator is also installed to regulate the operating pressure of thefeed system.
Specifications: Pressure regulated : 7-70 bar
Allowable flowrates : 3.8 - 38 liter/min.
2.3 Tanks and Cooling/Heating System
The TR 14 unit is supplied with a feed tank and a product tank, both having maximumcapacity of 15 liters. The feed and product tanks are made of stainless steel for corrosionand chemical resistance. The retentate line is equipped with a unit of thermostat as heatexchanger.
2.4 Water Flow Meter
The TR 14 unit is supplied with a Hedland turbine flow meter.
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3.0 SUMMARY OF THEORY
Membrane separation technology has evolved from a small-scale laboratory technique to a large-scale industrial process during the past 30 years. A classification of major types of membraneprocesses is given in Figure 4. Numerous theoretical models for ultrafiltration, nanofiltration, andreverse osmosis have been proposed along with the identification of new factors controlling flux ormass transfer through membranes. The basic operating patterns are best outlined in terms of thehydrodynamic resistance resulting from the buildup of deposited materials on the membranesurface.
Figure 4: Tubular (multichannel) type of microfilter
The flux, J will be given by:
dt dV
A J
m
1= =
( )cm R Rv +
=( )[ ]mbm AVC Rv / +
(1)
For most biological materials, is a variable depending on the applied pressure and time (thecompressible deposit), so that the expression requires a numerical solution.
A useful method for the effects of cross-flow removal of depositing materials is to write:
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( )r d m R R Rv J
+
= (2)
Removal of solute by cross-flow is sometimes assumed constant, and equal to the convective
particle transport at steady state ( J ssCb
1 0,
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Typical operating patterns of ultrafiltration are shown in Figure 6c.
Figure 6. Typical dependence of membrane flux. (a) Applied pressure difference, (b) Solute concentration, (c)
Cross-flow velocity
Solution containing macromolecular gel-forming solute will form a gel on the surface of themembrane. The gel formation will contribute to formation of dynamic membranes. The mechanismis as follows:
Due to convective flux through the membrane a concentration of the solution at the surface Cw increases and eventually reaches a gel formation concentration Cg
b
w
C
C Ink J .=
(Figure 6b). The flux, J throughthe membrane depends on a concentration according to the relationship:
(4)
Combining Equations (1) and (4),
( )k C C
Inb
w
pm R R vP
+
= (5)
As long as concentration Cw is less than Cg, Cw will increase with pressure, but the moment Cw equals Cg , an increase in brings about an increase of the layer resistance Rp, and the flux willno longer vary with pressure (Figure 7a).
Assuming no fouling effect, the membrane resistance Rm
m Rv J
.
=
can be calculated from the flux equationbelow:
(6)
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The slope obtained from the plot of flux, J versus is equal tom Rv.
1
The retention of any solute can be expressed by the rejection coefficient, R.
( ) f f
V V n
C C n R
/1
)/(1
0
0= (7)
Where, f C is final macrosolute concentration in the retentate
0C is initial macrosolute concentration
0V is initial volume
f V is final retentate volume
This expression assumes complete mixing of retentate seldom accomplished due to concentrationpolarization. The apparent rejection coefficient depends on factors affecting polarization includingUF rate and mixing. For material entirely rejected, the rejection coefficient is 1 (100% rejection); forfreely permeable material it is zero.
Rejection is a function of molecular size and shape. Nominal cut-off levels, defined with modelsolute, are convenient indicators.
Fractional rejection by membranes with low MW cut-off spans a narrower range of molecular sizethan by more open membranes. For maximum retention of a solute, select a membrane withnominal cut-off well below the MW of the species.
Many biological macromolecules tend to aggregate so that effective size 3may be much larger thatthe native molecule, causing increased rejection. Degree of hydration, counter ions and stericeffects can cause molecules with similar molecular weights to exhibit very different retentionbehavior.
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4.0 OPERATING PROCEDURES
4.1 General Start-Up Procedures
1. Ensure all valves are initially closed.
2. Prepare a sodium chloride solution by adding 100 gram of sodium chloride into20 liter of water.
3. Fill up the feed tank with the salt solution prepared in step 2. The feed shallalways be maintained at room temperature.
4. Turn on the power for the control panel. Check that all sensors and indicatorsare functioning properly.
5. Switch on thermostat and make sure the thermo oil level is above the coil insidethermostat. Check that thermostat connections are properly fitted.
Note: Adjust the temperature at the thermostat to maintain feed temperature.6. The unit is now ready for experiments.
4.2 General Shut-Down Procedures
1. Switch off the plunger pump (P2).
2. Close valve V2.
3. Drain all liquid in the feed tank and product tank by opening valves V3 and V4.
4. Flush all the piping with clean water. Close V3 and V4, fill the clean water tofeed tank until 90% full.
5. Run the system with the clean water until the feed tank is nearly empty (this isfor cleaning purpose).
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5.0 EXPERIMENT PROCEDURES
5.1 Membrane Characteristic Study
Objective:
In this experiment, students will perform a characteristic study on 4 different typesof membranes. This experiment requires approximately 100 gram of sodiumchloride.
Procedures:1. Perform the general start-up procedures as described in Section 4.1.2. Start the experiment for Membrane 1. Open valves V2, V5, V7, V11 and V15.
3. To set the maximum working pressure at 20 bars, switch on the plunger pump
(P1) and slowly close valve V5. Observe pressure value at pressure gaugeand adjust the pressure regulator to 20 bars.
Note: Use a proper wrench to turn the adjusting screw at the pressureregulator (PR1) by turning clockwise to increase pressure and counter-clockwise to reduce pressure.
Warning: Do not operate pump in dry condition. Make sure V2 is opened.
4. Open valve V5. Then, set membrane maximum inlet pressure to 18 bars forMembrane 1 by adjusting the retentate control valve (V15).
5. Allow the system to run for 5 minutes. Start collecting sample from permeatesampling port and weigh the sample using digital weighing balance. Recordthe weight of permeates every 1 minute for 10 minutes.
Note: To collect sample, open valve V19 and simultaneously close valve V11.
6. Repeat the step 1 to 5 for Membrane 2, 3 and 4. Open and close therespective sets of valves and adjust the membrane maximum inlet pressurefor every membrane.
Membrane Open Valves(Step 2)Sampling
Valves
Retentatecontrol
valve
Membranemaximum inlet
pressure (bar)1 V2, V5, V7,V11 and V15.
Open V19 andclose V11 V15 18
2 V2, V5, V8,V12 and V16.Open V20 and
close V12 V16 12
3 V2, V5, V9,V13 and V17.Open V21 and
close V13 V17 10
4 V2, V5, V10,V14 and V18.Open V22 and
close V14 V18 8.5
7. Plot the graph of permeate weight versus time.
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6.0 SAFETY PRECAUTION AND MAINTENANCE
6.1 Safety Precautions
1. Never operate the pump when there is no liquid in the pipeline. It will causeserious damage to the pump.
2. High voltages exist and are accessible in the control panel. Return the unit toyour supplier for any servicing.
3. The system should not be subjected to shock, sudden impact, vibration,additional load, or permanent external action of aggressive vapors.
4. Never splash water to the control panel. This will cause body injury and damageto the equipment.
5. Never use your bare hand to test the AC Power Supply. It may cause hazardousinjury.
6. Leaking couplings or fittings should be carefully retightened. Replace anygaskets or seals if necessary.
6.2 Maintenance
1. Always check and rectify any leak.
2. After each experiment, drain off any liquids from the feed tank and producttank. Make sure that the feed tank, product tank and piping are cleanedproperly by flushing the system with water until no traces of chemical aredetected.
3. Dispose all liquids immediately after each experiment. Do not leave anysolution or waste in the tanks over a long period of time.
4. Wipe off any spillage from the unit immediately.
5. Check the lubricant oil level in the pump motor. Refill if the level is reducedbelow the red spot
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7.0 REFERENCES
Warren L. McCabe, Julian C. Smith, Peter Harriott, Unit Operations of Chemical Engineering, 5 th Edition, McGraw Hill, 1993
Christi J. Geankoplis, Transport Processes and Unit Operations, 3 rd Edition, Prentice HallInternational Edition, 1995
Perry, R.H., Green, D.W. and Maloney, J.O., Perrys Chemical Engineering Handbook, 6 th Edition,McGraw Hill, 1984
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APPENDICES
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APPENDIX A
SAMPLE TABLE FOR EXPERIMENT
Time (min)Weight of Permeates (g)
Membrane 1 Membrane 2 Membrane 3 Membrane 4
1
2
3
4
5
6
7
8
9
10
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APPENDIX B
SAMPLE EXPERIMENTAL RESULT
Time (min)Weight of Permeates (g)
Membrane 1 Membrane 2 Membrane 3 Membrane 4
1 13.58 36.22 83.9 214.5
2 26.43 70.37 149.3 398.9
3 39.32 100.33 207.4 560.7
4 48.12 142.36 268.3 728.6
5 63.82 192.31 329.9 894.5
6 89.02 235.42 391.5 1058.9
7 117.62 280.17 459.1 1237.38 155.49 328.53 514.1 1381.8
9 229.29 376.81 575.4 1542.3
10 259.69 425.51 638.5 1704.1
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APPENDIX C